Why use CSS3 box-sizing?

HTML & CSS
1

The way that I understanding is that IE used to use their own box-sizing calculations. Then others said, Naughty naughty Microsoft you must use the W3C specifications. Which they did - from version 6 and onwards.

So why has it been reintroduced back into web design with CSS3 box-sizing?

Can anybody give me a practical example of how this could be useful?

2

[http://css-tricks.com/box-sizing/](link 1)

[http://reference.sitepoint.com/css/moz-box-sizing](link 2)

Hope this helps